How does changing the vector of transport disc distraction affect the outcomes of surgery in patients of temporomandibular joint ankylosis with obstructive sleep apnea?

Purpose Temporomandibular joint ankylosis (TMJA) in children is associated with retrognathia, reduction in pharyngeal airway volume (PAV), and obstructive sleep apnea (OSA). Distraction-osteogenesis (DO) is the proven method in the management of OSA. There is paucity in literature about the effect of distraction vector on PAV. It can be expected that an oblique vector would improve PAV and relieve OSA. Thus, the study was designed to explore the feasibility, advantages, and disadvantages of this modified technique for managing TMJA and OSA simultaneously. Materials and method The investigators designed a prospective study on patients of TMJA with retrognathia. Ethical approval was obtained (IECPG-547/14.11.2018). In all patients, simultaneous ankylosis release and mandibular distraction were performed. Primary outcome variables were improvement in 3-dimensional (3D) PAV and maximal interincisal opening (MIO). Secondary outcome variables were changed mandibular length, distraction relapse, and re-ankylosis. Paired t -test and multivariate ANOVA were used to assess all the parameters. Result The study included 13 joints in 8 patients of TMJA with retrognathia (2 unilateral and 6 bilateral ankylosis) with mean age of 14.25 ± 7.37 years. Mean distraction performed was 19 ± 4.0 mm. There was a statistically significant improvement of PAV by 225% ( p = 0.002), a reduction in Epworth’s scale ( p = 0.017), an increase in MIO ( p = 0.001), and an increase in mandibular length. Three patients had re-ankylosis at the 25-month follow-up. Conclusion The results of the present study conclude that modification of distraction vector improves 3D PAV and MIO in TMJA patients, with the added advantage of a reduction in overall treatment time and improved patient compliance. Graphical Abstract